LzHash.h 881 B

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  1. /* LzHash.h -- HASH constants for LZ algorithms
  2. 2023-03-05 : Igor Pavlov : Public domain */
  3. #ifndef ZIP7_INC_LZ_HASH_H
  4. #define ZIP7_INC_LZ_HASH_H
  5. /*
  6. (kHash2Size >= (1 << 8)) : Required
  7. (kHash3Size >= (1 << 16)) : Required
  8. */
  9. #define kHash2Size (1 << 10)
  10. #define kHash3Size (1 << 16)
  11. // #define kHash4Size (1 << 20)
  12. #define kFix3HashSize (kHash2Size)
  13. #define kFix4HashSize (kHash2Size + kHash3Size)
  14. // #define kFix5HashSize (kHash2Size + kHash3Size + kHash4Size)
  15. /*
  16. We use up to 3 crc values for hash:
  17. crc0
  18. crc1 << Shift_1
  19. crc2 << Shift_2
  20. (Shift_1 = 5) and (Shift_2 = 10) is good tradeoff.
  21. Small values for Shift are not good for collision rate.
  22. Big value for Shift_2 increases the minimum size
  23. of hash table, that will be slow for small files.
  24. */
  25. #define kLzHash_CrcShift_1 5
  26. #define kLzHash_CrcShift_2 10
  27. #endif